Free balance escapement



J. ENKLE FREE BALANCE ES CAPEMENT Filed Nov. 14, 1931 Patented Oct. 15, 1935 UNITED STATES PATENT OFFICE Application November 14, 1931, Serial No. 575,068 In Germany November 14, 1930 1 Claim.

This invention relates to balance escapements in which the outer end of the balance spring is not fixed to a base plate but connected to a movable element in order to make the balance escape- 5 ment free from direct actions of the movement.

According to the invention the movable element to which the outer end of the balance spring is attached is formed by a pallet wheel having pin pallets arranged around its entire circumfer- 10 ence and this wheel not only receives an oscillating movement but also a slight progressive rotary movement with the balance wheel after every second oscillation occurring with the unwinding of the balance spring, so that the pallet wheel and 15 the balance wheel, rotate once around their axes after performing a certain number of oscillating movements, the pallet wheel being, according to the invention, fed one pallet after each second oscillation by means of an intermediate mechanism.

20 The drive of the balance is effected at each feed movement of the pallet wheel by this feed movement.

One embodiment of the invention is illustrated by way of example in the accompanying drawing,

25 in which:

Fig. 1 shows a bottom plan view of one form of construction, the bottom plate being removed.

Fig. 2 is a vertical section of Fig. 1.

Figs. 3 and 4 illustrate the operation of this form of construction.

In the form of construction illustrated in Figs. 1 and 2, which comes into question particularly for long springs and slowly oscillating balances, the balance a is mounted on a pillar 1) between 35 this pillar and the cover plate 0. The pillar b is fixed in the bottom plate (1 and forms the axle, around which a pallet wheel e loosely rotates. The pallet wheel e carries ten pins f to f uniformly distributed on its under side and a pin g 40 on its upper side. The outer end it of the balance spring is connected to this pin 9. The inner end of the spring i is connected to the axle o of the balance a. In the path of the pins to f of the pallet wheel e a star wheel 1) serving as escape.-

45 ment wheel having three arms k to k is situated. Each of the arms k to k is provided with rest projections s and t. The axle Z of the star wheel 1) is mounted in bottom plate at and in a bracket in and carries a pinion n meshing with the train of 50 the clock (not shown).

The operation itself is as follows:--

Suppose the escapement be in the position illustrated in Fig. 1, according to which the arm k bears against the pin f and thus prevents the 55 star wheel p from rotating. Suppose also the balance (1 moves at first still in anticlockwise direction, that is in the direction of the arrow at. During this direction of movement of the balance and the assumed position of the escapement parts the spring 1' exerts a pressure on the arm 10 5 through the intermediary or" the pallet wheel 6 by means of the pin f which pressure, apart from the fact that it ensures the checking effect of the pallet wheel 6 on to the star wheel p, remains ineffective. When the balance a has completed its 10 movement in the direction of the arrow at, it reverses its direction of movement in known manher, so that it moves then in clockwise direction. During this clockwise movement a time arrives, when the pallet wheel 6 is rotated in clockwise direction by the balance a through the intermediary of the spring i. As soon as this occurs, the star wheel p is freed by the'pulling back of the pin f into the position shown in Fig. 3. This star wheel then rotates under the action of the train in the direction of the arrow y, the arm k acting on the pin i of the pallet wheel 6 and shifting same in the direction of the arrow :1: until the arm 10 slides off the pin f*.

The pallet wheel 6 moves on a short distance owing to its kinetic en rgy so that the advance side of the arm k reliably slides off the pin f and does not remain with the outer surface of its projection 8 bearing against the pin f The movement of the pallet wheel e is impeded by the spring i which opposes with increasing resistance the feed of the pallet wheel e by the star wheel. Under this opposition the pin i only moves so far beyond the projection 5- cf the arm k that this arm can reliably slide off the pin i whereupon the pallet wheel 6 immediately commences to rotate in clockwise direction under the action of the spring 1' and consequently brings the pin f in front of the projection t of the arm k of the star wheel so that the position indicated in Fig. 4 is actually reached.

The increasing resistance of the spring 2 on the pallet wheel e is caused by the fact that, during the whole feeding movement of the pallet wheel e by the star wheel and the temporary locking thereof by the pin 1, the balance wheel a swings in clockwise direction, that is retains its direction of movement which alone effects the lifting of the pin ,1 from the arm k Thus the pallet wheel e is moved against the action of the balance wheel a on the pallet wheel and consequently a gradually increasing tensioning of the spring 2' must take place. The pallet wheel e is not an unloaded element caused to swing by the star wheel, but is subjected to a resistance which, as already mentioned, causes the pallet wheel to swing out only slightly beyond the projection s of the arm k Only when the position shown in Fig. 4 has been reached, does the balance wheel a change its direction of movement and then rotate in the direction of the arrow as. The locking of the arm 70 by the pin f is then disengaged and at the same time the arm k is locked by the pin f Only when the kinetic energy in the balance wheel has been overcome by the tensioning in the spiral spring 2' by the engagement of the pin f with the arm k is the balance wheel a caused to again reverse its movement.

I claim:

A free balance escapement, comprising in combination a balance wheel, a spiral spring connected at its inner end to said balance wheel, a pallet wheel connected to the outer end of said spring and fitted with pins uniformly distributed around its circumference, and a driven star wheel acting as escapement wheel and having arms extending within the path of said pins, each of said arms adapted to successively cooperate with one of said pins to arrest the movement of said star wheel and pallet wheel and thereby tension said spring to reverse the movement of said balance wheel and of said pallet wheel to disengage said pin and allow said star wheel to rotate through substantially an angle equal to the angle between adjacent arms and said pallet Wheel through substantially an angle equal to the angle between adjacent pins, said star wheel being then arrested by the next following pin of said pallet wheel.

JOSEPH ENKLE. 

